Method of and apparatus for segregating foreign particles from a tobacco flow

ABSTRACT

The invention relates to a method of segregating foreign particles from a tobacco flow. The invention moreover relates to an apparatus for segregating foreign particles from a tobacco flow, which comprises a first conveyor feeding the tobacco to a device for detecting foreign particles as well as a device for segregating foreign particles. The apparatus according to the invention is characterized by the following steps of operation: conveying tobacco by means of a first conveyor, with the tobacco being held on said first conveyor by means of suction air, detecting foreign particles in said tobacco flow constituted by the conveyed tobacco in the zone of said first conveyor or downstream of said first conveyor, and segregating detected foreign particles from said tobacco flow. The apparatus according to the invention is characterized by the feature that the first conveyor is configured for holding tobacco by suction air.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 10 2004 015 468.6-23 filed on Mar. 26, 2004. The disclosures of the foregoing application and each U.S. and foreign patent and patent application mentioned herein are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of and an apparatus for segregating foreign particles from a tobacco flow.

2. Discussion of Background Information

A corresponding method and a corresponding apparatus are known from the U.S. Pat. No. 6,332,543 B1, In that known apparatus, respective conveyors are provided for conveying a tobacco flow. An oscillatory trough is used which is joined by a conveyor belt on the downstream side, with the latter being joined by a pair of conveyor belts on the downstream side, which form a channel. Downstream of the channel, a device is provided for detecting foreign particles, which, according to the U.S. Pat. No. 6,332,543 B1, comprises a laser detector that emits a laser beam onto objects (tobacco and foreign particles) of the tobacco flow and that measures the reflection. A standard reference drum is disposed behind the tobacco flow, seen along the direction of the laser beam, which is matched to the color of the tobacco used. Downstream of the device for detecting foreign particles, a device is provided for segregating foreign particles in the form of a nozzle that is operated whenever foreign particles are detected, which causes segregation of the foreign particles from the tobacco flow by means of compressed air.

SUMMARY OF THE INVENTION

It is the object of the invention to improve an appropriate method of the claimed general type in such a way that a more rapid tobacco conveyance or a higher speed of the tobacco flow will become possible.

The object of the invention is attained through a method for segregating foreign particles from a tobacco flow, comprising the following steps:

-   -   conveying tobacco by means of a first conveyor, with the tobacco         being held on said first conveyor by means of suction air,     -   detecting foreign particles in said tobacco flow constituted by         the conveyed tobacco in the zone of said first conveyor or         downstream of said first conveyor, and     -   segregating detected foreign particles from said tobacco flow.

On account of the method according to the invention and particularly by conveyance of the tobacco in the form of a tobacco flow on the first conveyor by holding by means of suction air, it is possible to realize a distinctly higher conveying speed of the tobacco flow. Due to the higher conveying speed of the tobacco flow it is possible to use an appropriate apparatus that presents definitely smaller dimensions at the same throughput of tobacco. The method according to the invention is preferably applied in tobacco processing. In this manner, tobacco leaves, tobacco strips and similar objects are efficiently freed of foreign particles. Due to the use of suction air the additional advantage is achieved that the tobacco flow is substantially present in a mono layer of tobacco so that the efficiency in the detection of foreign particles is distinctly enhanced.

A particularly thin tobacco flow or a tobacco flow, respectively, which consists substantially of a mono layer of tobacco, can be efficiently achieved in a simple manner when a second conveyor is provided from which or onto which the tobacco is transferred to or from the first conveyor. An efficient transfer is possible when a stream or jet of air is used for transfer of the tobacco. In such a case, suction air is employed in particular. Within the scope of the present invention, the term “tobacco” is meant to denote tobacco leaves, tobacco strips, leaf tobacco and cut tobacco in particular.

An efficient control of the process is possible if the first conveyor is disposed above the conveyed tobacco. On account of this provision, tobacco must be aspirated from the first conveyor so that actually only a single mono layer of tobacco is created in the tobacco flow. According to an alternative, the first conveyor is arranged underneath the conveyed tobacco. When the tobacco flow is conveyed for discharge by suction air after at least one of detection of foreign particles and segregation of foreign particles, a high conveying speed of the tobacco flow can be retained.

The object of the invention is furthermore attained through an apparatus for segregating foreign particles from a tobacco flow, comprising a first conveyor feeding the tobacco to a device for detecting foreign particles, and a device for segregating foreign particles, wherein the first conveyor is configured for holding tobacco by suction air. With this configuration, a very rapid conveyance of the tobacco by means of the first conveyor becomes possible. The first conveyor preferably comprises a suction belt. When a second conveyor is provided for conveying tobacco into the region of the first conveyor it is possible in a simple manner to realize a very thin layer of tobacco in the tobacco flow. In this way, it is possible to achieve substantially a mono layer of tobacco in the tobacco flow.

A particularly efficient transfer from the second conveyor to the first conveyor, or vice versa, is possible when the second conveyor comprises an element permeable to air and when the second conveyor is an oscillatory trough having a bottom permeable to air. The conveying speed of the tobacco flow may remain at a very high level when a suction device is provided downstream of the device for detecting foreign particles. The suction device may also be arranged downstream of the device for segregating foreign particles.

Provisions are preferably made for a conveying speed of the conveyed flow on the first conveyor of at least 5.5 m/s. A conveying speed of up to 11 m/s is preferably provided. Hence, a conveying speed of the tobacco flow is possible which is distinctly higher than the conveying speed according to prior art. The latter speed is typically in the range of up to 5.5 m/s. At the same mass flow of 9,000 kg/h, for example, then a useful width is achieved according to the invention which ranges between 1.6 m and 0.8 m, Due to the mono layer or quasi-mono layer of the tobacco in the tobacco flow by the time of detection of foreign particles the latter is highly efficient because the camera or the laser scan or a device for optical detection of foreign particles, respectively, which is to be provided preferably, allows unobstructed view or access to the tobacco surface. As a result, a very high efficiency becomes possible in the segregation of foreign particles from the tobacco flow.

Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further explained in the detailed description which follows with the aid of exemplary embodiments, but without limiting the general inventive idea, in reference to the drawing.

FIG. 1 shows a schematic illustration of an apparatus according to the invention for segregating foreign particles from a tobacco flow.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.

In the figures the same or similar elements or corresponding parts are respectively provided with the same reference numbers, so that a corresponding renewed introduction is unnecessary and only deviations of the exemplary embodiments in these figures from the first exemplary embodiment are explained.

Tobacco 10 is fed onto an oscillatory trough 17 along the feeding direction 12. The oscillatory trough 17 comprises a bottom 28 that is perforated and hence permeable to air. A tobacco flow 11 is formed in the oscillatory trough 17, which is carried into the region of a suction belt conveyor 14. The suction belt conveyor 14 comprises a suction belt 15 that is configured for rotation around two guiding rollers in the direction of the arrow. Moreover, a suction box or a suction zone 16 is provided so that suction air is blown from below the suction belt conveyor into the suction zone 16. The suction air is identified by the reference numeral 27. The suction belt 15 is configured in the form of a tissue permeable to air so that respective air currents may pass therethrough. Tobacco 10 and foreign particles 18 arrive through the suction air 27, indicated by the arrows meant to represent a direction of transfer 13, on the underside the suction belt where they are held by the suction air 27.

As the suction air flow is less strong in a zone where tobacco has already been fed onto the suction belt, and is thus fully effective in the intermediate zones, further portions of the tobacco flow, which have been lifted off, drawn, sucked or conveyed from the oscillatory trough 17 towards the suction belt in the form of tobacco 10 or foreign particles 18 primarily move into the interspaces so that substantially a mono layer of a tobacco flow is formed on the suction belt conveyor 14 or underneath the suction belt conveyor 14, respectively. The suction 16 of the tobacco flow conveyed along the conveying direction 20 does no longer produce its effects in the zone of the right-hand belt return so that the particles move along a parabolic curve further to the right downward side into the zone of a device for detecting foreign particles. In this case, the device for detecting foreign particles consists of an optical detector 21 that emits a beam of light 22 or a cone of light 23 onto the tobacco flow and measures the reflected beams. To this end, a reference element 23 is provided, too, which is or may be matched with the color and brightness of the tobacco flow. When a foreign particle is detected, this foreign particle 18 may be segregated along the segregating direction 19 by means of a segregating nozzle 24 from which compressed air 25 is discharged, at a site shortly downstream (at a distance of roughly 50 to 150 mm) of the device for detecting foreign particles, seen along the conveying direction.

The remaining tobacco flow is discharged by suction 25 in the exhaustion duct 29. According to the invention, the tobacco 10 is accelerated, in suspended position, on the underside of a suction belt 15 to the required speed level. At least a duplication of the common speed according to prior art to roughly 11 m/s is possible and thus also a device that presents a conveying width as small as roughly one half.

A non-occupied suction belt 15 includes a defined suction zone that is predetermined by the exhaustion zone 16 or the suction box 16, respectively. As long as there is no adhering product, suctioning is uniform. When the suction belt 15 is occupied already in parts with tobacco or foreign particles, the occupied locations are no longer or less operative in suction. Only the non-occupied locations permit suction with a suction force corresponding to that of the non-occupied suction belt. Thus, double or multiple occupations of the same positions is prevented while a substantially genuine mono layer is created.

The product in the form of the tobacco flow is conveyed into the region underneath the suction belt, for instance via an oscillatory trough 17 or by means of another conveyor that is preferably perforated, too. Due to the perforation of the bottom 28 of the oscillatory trough 17 or the perforation of another conveyor an unobstructed air flow is possible in the zone between the oscillatory trough 17 or the other conveyor and the suction belt conveyor 14. The product, i.e. tobacco 10 and foreign particles 18, is lifted off the oscillatory trough 17 by the suction belt 14 and adheres substantially in a mono layer to the underside of the suction belt 15. At the end of suction zone of the suction belt 15, the product (tobacco) and foreign particles are projected along a flight path in the form of a trajectory parabola that may also be influenced by the suctioning of the suction air 26 into the exhaustion duct 29 at a speed of preferably 5.5-11 m/s through the scanning zone of the optical system for detection of foreign particles. Foreign particles that are detected are selectively removed from the product flow or the tobacco flow, respectively, by the precluding or segregating device in the form of the air nozzle 24 in the same zone or at a short distance behind the zone.

To prevent subsequent deceleration of the product (tobacco) upon its output from the suction zone of the suction belt, the product is guided into a duct within the region where foreign particles are detected, or at a short distance behind this region or behind the segregating zone, which duct holds an adjustable vacuum. The product is sucked into this exhaustion duct and thus does not reduce its speed.

It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words of which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.

List of Reference Numbers

-   -   10 tobacco     -   11 tobacco flow     -   12 feeding direction     -   13 transfer direction     -   14 suction belt conveyor     -   15 suction belt     -   16 suction zone     -   17 oscillatory trough     -   18 foreign particles     -   19 direction of segregation     -   20 conveying direction     -   21 optical detector     -   22 beam of light     -   23 reference element     -   24 segregating nozzle     -   25 compressed air     -   26 suction air     -   27 suction air     -   28 bottom     -   29 exhaustion duct 

1. A method of segregating foreign particles from a tobacco flow, including the following steps: conveying tobacco by means of a first conveyor, with the tobacco being held on said first conveyor by means of suction air, detecting foreign particles in said tobacco flow constituted by the conveyed tobacco in the zone of said first conveyor or downstream of said first conveyor, and segregating detected foreign particles from said tobacco flow.
 2. The method according to claim 1, characterized in that a second conveyor is provided from which the tobacco is transferred to said first conveyor.
 3. The method according to claim 1, characterized in that a second conveyor is provided onto which the tobacco is transferred from said first conveyor.
 4. The method according to claim 3, characterized in that a stream of air is used to transfer the tobacco.
 5. The method according to claim 2, characterized in that a stream of air is used to transfer the tobacco.
 6. The method according to claim 1, characterized in that said first conveyor is disposed above the conveyed tobacco.
 7. The method according to claim 1, characterized in that said first conveyor is disposed underneath the conveyed tobacco.
 8. The method according to claim 1, characterized in that said tobacco flow is conveyed for discharge by means of suction air after at least one of detection of foreign particles and segregation of foreign particles.
 9. An apparatus for segregating foreign particles from a tobacco flow, comprising a first conveyor feeding the tobacco to a device for detecting foreign particles, and a device for segregating foreign particles, characterized in that said first conveyor is configured for holding tobacco by suction air.
 10. The apparatus according to claim 9, characterized in that said first conveyor comprises a suction belt.
 11. The apparatus according to claim 9, characterized in that a second conveyor is provided for conveying tobacco into the region of said first conveyor.
 12. The apparatus according to claim 11, characterized in that said second conveyor comprises an element permeable to air.
 13. The apparatus according to claim 9, characterized in that a suction device is provided downstream of said device for detecting foreign particles.
 14. The apparatus according to claim 9, characterized in that a conveying speed of said first conveyor of at least 5.5 m/s is provided. 